Method for obtaining acid dye uniformity in polyamides

ABSTRACT

POLYAMIDES HAVING INCORPORATED THEREIN A SMALL AMOUNT OF A CERTAIN HINDERED PHENOL OR A CERTAIN QUINOLINE COMPOUND POSSESS EXCEPTIONAL ACID DYE UNIFORMLY.

United States Patent Oflice 3,573,244 Patented Mar. 30, 1971 3,573,244 METHOD FOR OBTAINING ACID DYE UNIFORMITY IN POLYAMIDES Phil H. Wilken, Dayton, Ohio, and Graham Leadbetter, St. Louis, Mo., assignors to Monsanto Company, St. Louis, Mo. No Drawing. Filed Oct. 16, 1968, Ser. No. 768,189 Int. Cl. C08g 51/60, 51/66 US. Cl. 260-453 3 Claims ABSTRACT OF THE DISCLOSURE Polyamides having incorporated therein a small amount of a certain hindered phenol or a certain quinoline compound possess exceptional acid dye uniformity.

BACKGROUND OF THE INVENTION Recently, due to the increasing popularity of bright colored wearing apparel and textile fabrics in general, the application of dyes onto nylon textile yarns or onto fabrics prepared therefrom has received much attention. Briefly, nylon textile yarns are prepared in the following manner: the nylon is spun into filaments which are gathered into yarn; the yarn is drawn to give it strength; textured to give it a good hand; heat-set to retain its textured shape; and then dyed to a desired color. Although nylon can be dyed with acid type dyes to bright colors, unfortunately prior to dyeing, yarn or fabric is subjected to heat, such as that encountered during texturing and heat-setting treatments, which causes acid dye sites (amine end groups) to be removed from the nylon molecules. As a result the yarn, when subsequently treated with acid type dyes, does not dye uniformly, that is, the color of the dyed yarn has a streaked appearance. Obviously, dye non-uniformity characteristics of this nature cannot be tolerated if a commercially acceptable textile yarn is to be achieved.

A primary object of the present invention therefore is to provide a nylon textile yarn which tends to retain its acid dye sites when subjected to heat.

SUMMARY OF THE INVENTION In accordance with the present invention, the tendency of nylon to lose amine end groups when subjected to heat is substantially reduced by incorporating therein from 0.01% to 5.00% by weight of a compound selected from the group consisting of certain hindered phenols and certain quinoline compounds.

As used herein, reference to loss of amine end groups denotes that the amine end groups have undergone a structural modification and no longer will receive acid type dyes. It has been discovered that when nylon yarns have been subjected to temperatures of from 180 to 220 C. or higher for only short periods of time, for example from one to ten minutes, 7.5% to 100% of their amine end groups are lost. On the other hand nylon yarns containing an additive of the type described show a significant reduction in the loss of amine end groups when subjected to heat.

PREFERRED EMBODIMENTS OF THE INVENTION Suitable phenols for use in the present invention are those recognized in the art as heat stable, hindered phenols having at least one group of the structure in which R and R are each a substituent group, such as a C to C alkyl group,

\CH2/n or hydrogen, wherein n is an integer of from 1 to 3, and which are characterized in that at least one R group is a branched alkyl group, preferably branched on the alpha carbon. Commercially available phenols of this type generally are those in which R is either H, CH -C H or CH,,; one R is either H, -CH;,- or -C(CH and the other R is --C(CH The symbol t is used hereafter to designate the tertiary butyl group. Representative compounds of this type include the following compounds, which compounds are hereafter identified by reference to the letter preceding their structure:

A. (3113 on, on om 0Q, 0H 0H 2,4,-6 tris(3-tert-butyl-5-methyl-2-hydroxybenzyl) phenol 1, 3 ,5 -:t-rimethyl-2,4, 6-tris 3 5-di-tert-buty1-4- hydroxybenzyl)benzene O. OH

l CHgCHzC O O CiaHay octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate D. ll?

di (3,5-di-tert-bIutyl--hydroxy) benzyl ether CzHs C2H5 2,2 methylenebis (4-ethy1-6-ter t-bulty1 phenol) CH3 CH3 2,2 -meti1ylenebis (4-111ethyl-fi-Itert-butylphenol) I JH CHzCHzCHa I;

4,4 buty11denebis (fi terlbbutyl-m-cresol) t t I CH3 CH3 4,4' thiobis(G-tert-butyl-m-cresol) 4,4'-thiobis di-sec-amylphenol) -2, G-di-terbbutyl-alpha phospho-di-stearyl) para-cresol CHzOY tetra[metl1ylene-3,-(3,5-di-t-butyl-4-hyd1'Oxyphenyl) propionate] methane 11 I I CHzCHzt t I 4,4 methyleuebis(2,6-di-tent-butylpheul) (2,6-di-tert-bmtyl) -alpha-dimethylaminmpnrwcresol O. t t I I I CH3 CH3 4,4-thiobis (G-te rt-butyl) -ortho-cresol The above phenols are intended to be representative only and it will be apparent to those skilled in the art that numerous other hindered phenols could also be used in practicing the invention. These phenols all contain the characteristic type 2,2,4-trimethyl-6-ethoxy-1,2dihydroquinoline Q. OH:

2,2,4-trimethyl-6-phenyl-1,2-dihydroquino1ine OH: H

X=number of recurring molecules poly-methyl-quinoline: a resin formed by heating 2,2,4- trimethyl-1,2-dihydroquinoline in the presence of sulfuric acid.

The additive may be incorporated into the nylon at any time prior to spinning. Preferably, the additive is added to the nylon salt solution prior to polymerization. The amount of additive may vary over a widerange, e.g., from 0.01% to 5% or more by weight based on the weight of nylon, and is dependent upon the degree of amine end group protection desired as well as the temperatures involved in processing the yarns. Generally, from 0.1 to 1.0% by weight of the additive afiords optimum protection of the amine end groups. If desired, other additives, such as delustrants, viscosity stabilizers, plasticizers, antistatic agents and the like, may also be incorporated into the nylon.

The phenol or quinoline additive may be incorporated into any type nylon, i.e., synthetic linear polycarbonamides containing recurring carbonamide linkages as an integral part of the polymer chain. The nylons are formed by polymerization of the diamine and dicar'boxylic acid, or by self polymerization of an aminoacid or lactam, or by polymerization of a mixture of these compounds. Representative nylons include nylon 6, nylon 66, nylon 11 and the like. These nylons are conveniently prepared according to procedures well known in the art and commonly employed in the manufacture of simple nylons, such as nylon 66. That is, the reactants, usually an aqueous solution of the diamine/acid salt, e.g., hexamethylene diammonium adipate, are heated at a temperature of from 180 C. to 300 C. with continuous removal of water until the product has a sufficiently high molecular weight to exhibit fiber-forming properties, which properties are reached when the polymer has an intrinsic viscosity of at least 0.4 as determined in rn-cresol.

The invention is further explained by means of the following examples. These examples are for illustrative purposes only and are not to be considered a limitation of the invention.

EXAMPLE 1 To a stainless steel evaporator there was added 8.47 moles of water containing 0.562 moles of hexamethylene diammonium adipate salt dissolved therein. The unit was purged with nitrogen and then pressurized to 13 p.s.i.g. The solution was heated to 137 C. with continuous removal of steam condensate. At this point the salt concentrate was piped under pressure into a stainless steel high pressure autoclave which had been purged previously with nitrogen. In this autoclave, which was equipped with a stirrer for agitation, the pressure was immediately raised to 250 p.s.i.g. and the temperature was raised to 220 C. The steam was removed until the polymer melt temperature reached 243 C. and then the pressure was gradually reduced over a 25-minute interval to atmospheric pressure and the polymer permitted to equilibrate for 30 minutes at 278 C.

The polymer so produced was melt spun at 280 C. directly from the bottom of the autoclave through a 13-hole spinneret yielding white filament yarns. These yarns (control) were drawn over hot pins (90 C.) under a maximum draw ratio of 5.65 times their original length.

EXAMPLES 2-15 Nylon 66 yarns were prepared in the same manner as in Example 1 with the exception that the following additives in the amounts indicated were incorporated into the salt solutions:

Amount, percent Additive by weight Exagnple:

To determine the affect of heat upon the acid dye uniformity of the yarns of Examples 1-15, a sample of each yarn was dyed prior to being subjected to heat and a second sample thereof was dyed after being heated in an oven for ten minutes at 190 C.

Dyeing of the yearns was carried out by immersing samples in a test tube containing 25 ml. of 0.75% Scarlet 4RA Conc. CF(C.I. Acid Red 18) acid dye solution adjusted to a pH of 3.1 with the addition of formic acid and capping the tubes. The tubes were then placed in a rotating steam bath at 100 C. for 2 hours. The percent dye absorbed on the fibers was determined by pipetting 5 ml. of the dye liquor, diluting to 100 ml. and measuring the optical density at 510 mu. These values were subtracted from a blank determination (no fiber) to give the amount of dye on the fiber. The results of these determinations are given in the table below and are expressed by computing the fraction: percent dye (initial)percent dye (final)/percent dye (initial). The numerator rep resents the change in dye uptake at saturation observed between two samples of identical composition, one of which had been heated at 190 C. for ten minutes prior to dyeing and the other sample which received no heat treatment prior to dyeing. The results are expressed as a fraction of the initial dye uptake since the change in dye uptake is a function of the initial amine end group content.

TABLE [Influence of various additives on the acid dye uniformity of nylon 66] Amount, Percent Percent Percent dye initial percent dye dye percent dye final/ Additive wt. initial final percent dye initial The results in the above table clearly indicate that the acid dye uniformity of nylon 66 yarn is substantially improved by the additives of the present invention. Of the additives tested the additive designated as R imparted the best acid dye uniformity. Additives K, A and B also imparted excellent acid dye uniformity to the yarn. Although the invention has been illustrated with reference to nylon 66 yarn containing certain hindered phenols and quinoline compounds, the acid dye uniformity of nylon yarns in general can be improved by incorporating therein additive amounts of a hindered phenol or a quinoline compound of the type described herein.

We claim:

1. A linear fiber-forming polyamide having recurring carbonamide groups as an integral part of the main polymer chain and containing incorporated therein from about 0.01 to 5% by Weight, based on the weight of the polyamide, of polymeric 2,2,4-trimethyl-1,2-dihydroquinoline.

2. A linear fiber-forming polyamide having recurring carbonamide groups as an integral part of the main polymer chain and containing incorporated therein from about 0.01 to 5% by weight, based on the weight of the polyamide, of 2,2,4-trimethyl-6-ethoxy-1,2-dihydroquinoline.

3. A linear fiber-forming polyamide having recurring carbonamide groups as an integral part of the main polymer chain and containing incorporated therein from about 0.01 to 5% by weight, based on the weight of the polyamide, of 2,2,4-trimethyl-6-phenyl-1,2-dihydroquinoline.

References Cited UNITED STATES PATENTS 2,630,421 3/ 1953 Stamatoif 26045.8 3,105,732 10/1963 Ortheil 8-21 3,234,290 2/1966 Rocklin 260624 3,351,678 11/1967 McBurney 260897 3,362,930 1/1968 Kehe 26045.8 3,367,870 2/1968 Spivack 25249.8 3,379,676 4/1968 Ashton et a1 26045.8 3,407,140 10/1968 Chiddix et al. 25247.5 3,410,648 11/1968 Mautner et al. 8-55 3,454,412 7/1969 Stokes l06287 3,493,633 2/1970 Lange 260- 857 DONALD E. CZAJA, Primary Examiner R. A. WHITE, Assistant Examiner U.S. Cl. X.R. 

